21. If gear B moves around gear A about a fixed arm then the motion is called

- Rotatory motion
- Epicyclic motion
- Simple pendulum motion
- Parabolic motion

22. The minimum required centre distance of two mating spur gears is decided based on

- Surface compressive strength of the gear
- Bending strength of the gear material
- Ultimate strength of the gear material
- Fatigue strength of the gear material

23. The reciprocal of speed ratio is called

- teeth ratio
- gear ratio
- train value
- size ratio

24. Tangent to a __________ is normal to an involute in involute teeth gears.

- base circle
- deddendum cricle
- crest circle
- none of the above

25. Double helical gears are also called

- Hypoid gears
- Bevel gears
- Herringbone gears
- Spiral gears

26. The ratio of base circle radius and pitch circle radius in an involute gear is equal to

- cosφ
- sinφ
- tanφ
- cosecφ

27. In spur gears, the circle on which the involute is generated is called

- Base circle
- Pitch circle
- Clearance circle
- Addendum circle

28. The height by which a tooth of a gear projects beyond the standard pitch circle or pitch line is technically known as

- Addendum
- Dedendum
- Backlash
- Pitch radius

29. The function of differential gear in automobiles is to

- facilitate reverse operation of the vehicle
- reduce tyre wear at high speeds
- distribute equal torque between wheels
- take care of difference in speeds of rear wheels

30. Which type of gear will be used for non-intersecting perpendicular shafts?

- helical gears
- spur gears
- hypoid gears
- herring bone gears